1. Field of the Invention
The present invention relates to a self-light emitting device panel in which pixel trios each including a set of three light-emitting devices which emit light of three primary colors respectively are arranged in matrix in a row direction and a column direction. The invention also relates to an image display device including a data driver and a scan driver driving the self-light emitting device panel. The invention further relates to a passive driving method of self-light emitting devices capable of alleviating a row wiring pitch of drive lines extending in the column direction.
2. Description of the Related Art
The image display device in which LED light emitting devices (self-light emitting devices) of three primary colors (RGB) are arranged in matrix is known. Sub-pixels of respective colors of RGB construct one pixel. Alternatively, three pixels of RGB form one pixel trio. Hereinafter, the latter notation is applied in the specification of the invention.
In the image display device, there are a system in which active drive (also referred to as matrix drive) is possible by providing switches in respective pixels and a system in which passive matrix drive is possible by including just an LED and wiring for supplying current to the LED in each pixel. The passive matrix drive is one of passive driving systems as it is the system driven without through the switch of each pixel.
When the vertical direction of a pixel array is set as a column direction and the horizontal direction thereof is set as a row direction, wiring lines in the column direction are called column lines and wiring lines in the row direction are called row-scanning lines. In the passive matrix drive system, one light-emitting device is connected to each intersection between the column line and the row-scanning line.
The image display device normally includes the data driver and the scan driver within a display panel or as external attachment.
The data driver performs current driving or voltage driving of respective N-pieces of column lines corresponding to the number of pixels in the horizontal direction of a display screen so as to obtain luminance corresponding to data values.
The scan driver line-sequentially scans respective M-pieces of row-scanning lines corresponding to the number of pixels in the vertical direction to thereby selectively form paths of current flowing through the self-light emitting devices by the data driver.
In the image display device of the passive driving system, the self-light emitting devices are directly connected between arbitrary column lines and row-scanning lines. The data driver applies, for example, a voltage value capable of allowing current corresponding to pixel tones to N-pieces of column lines arranged at equal intervals in the row direction all at once. At that time, the scan driver allows one arbitrary row-scanning line to be in a state of applying current through the line (active state) and repeats the state line sequentially in the column direction to thereby perform scanning.
At this time, as LEDs are line-sequentially driven in the passive driving, LEDs in one line (hereinafter, referred to simply as a pixel line) emit light for only a period of time obtained by dividing a scanning period (V-period) of one screen by the number of pixels in the column (vertical) direction at the maximum. For example, in the image drive device having 1920×1080 pixels corresponding to FHD (Full High Definition), one pixel line emits light for a period of 1/1080 of the V-period.
Accordingly, in order to obtain necessary luminance, a method of increasing the peak luminance at the time of lighting the LEDs instantaneously and the like can be considered. However, electric current to be applied to the LEDs is limited by various reasons, therefore, it is difficult to obtain necessary display luminance (brightness per a unit area in the display screen) particularly in a large screen.
On the other hand, luminance can be increased by allowing the lighting period of time to be longer by adding a drive circuit to each LED in the active drive system, therefore, the large screen image display device generally applies the active drive system.
However, in the active drive system, the circuit for controlling the lighting period is complicated, which increases costs.
Accordingly, as a method for increasing luminance while taking advantage of the passive driving system with low costs, a method of lighting plural pixel lines at the same time though the line-sequential scanning is proposed (refer to JP-A-2003-280586 (Patent Document 1) and JP-A-2009-037165 (Patent Document 2)).
In Patent Document 1, the method of dividing the display screen into plural screens and driving them at the same time is disclosed. According to the application of the method, display luminance is improved by driving plural pixel lines at a certain period of time as a whole display screen.
On the other hand, in Patent Document 2, plural pixel lines adjacent in the column direction are driven at the same time, and the drive of the plural pixel lines are scanned seamlessly so that pixel lines partly overlap.
The both methods are effective for improving low display luminance which is a disadvantage of the passive driving.